Vehicle interior trim panel with a soft-touch foam layer, and a method and apparatus for making the same

Abstract

An interior trim component such as a vehicle dashboard includes a substantially rigid and form-stable substrate of polypropylene and natural fibers, a supporting halo skeleton and other frame components heat fused onto the backside of the substrate, and a polyolefin foam layer as well as a decorative polyolefin cover film laminated onto the front side of the substrate. The foam layer has an increased thickness and a decreased foam density at sharply contoured or curved areas of the trim component, in comparison to the flat surfacial areas. As a result, the trim component has a desirable soft-touch characteristic and impact absorbing properties at all areas including protruding curves and edges. A method for forming such a trim component involves steps of pre-molding the foam layer and cover film by vacuum thermoforming, pre-molding the substrate by vacuum thermoforming, and then heat laminating the pre-heated, pre-molded substrate onto the pre-molded foam layer and cover film. The sharply curved or contoured areas of the component are provided with a greater tolerance spacing between the substrate and the cover film, which are held to the respective mold contours by vacuum. Under the effect of heat and the applied vacuum, the foam layer expands to have a greater thickness and a lower density in these sharply contoured areas.

Description

The invention relates to a trim component such as a trim panel or a dashboard for the interior of an automobile or other vehicle, having a foam layer that provides a "soft-touch" characteristic. The invention further relates to a method and an apparatus for making such a trim component.BACKGROUND INFORMATIONInterior trim components of the above mentioned general type, such as door trim panels and dashboards for automobiles, as well as methods and apparatus for forming such trim components are generally known in the art. However, the known products, methods and apparatus all suffer disadvantages, which the industry has long felt a need to overcome or improve upon. The automobile industry has come to require a "soft-touch" characteristic for high quality trim components. In other words, the surface of the trim components must feel soft or resilient, and not hard or rigid, to the touch. This requirement arises from impact protection considerations, and even more simply from consumer pr...

AI Technical Summary

Benefits of technology

According to the invention, the foam layer is not thinned or compressed in the areas of an edge or corner of the finished trim component. More particularly, the foam layer in the finished trim component has a lower density in the areas of the corners, edges and other sharply contoured areas. This is achieved by the method and apparatus according to the invention, in contrast to the prior art as discussed above. Namely, in the prior art methods involving molding and lamination of a foam sheet, the foam sheet necessarily became thinned, compressed, or even totally collapsed at sharply contoured areas, because the cover film and foam layer were heated, stretched, and compressed over the sharply contoured areas of the substrate in a molding apparatus. The present invention avoids this effect and the resulting loss of the soft-touch character at the sharply contoured areas, by providing a special molding method and apparatus that allow the initial thickness, density and cell structure of the foam layer to be maintained or even enhanced by the expansion of the foam layer during the molding process.

Furthermore, a dashboard or other trim component may be composed of several sections or segments that are individually manufactured according to the present invention, and then thermally welded together along the halo skeleton support frame in order to prepare the finished part. In this manner, a modular design and construction, and thus a flexible configuration of parts can be achieved without having to retool the manufacturing equipment. Also, different substrate materials can be used for different sections or segments of the part, to provide different physical properties as needed in different areas. For example, a substrate containing natural fibers can be used on the upper portion of a dashboard to provide impact energy absorption, while the bottom side of the dashboard may use a plastic substrate.

Problems solved by technology

However, the known products, methods and apparatus all suffer disadvantages, which the industry has long felt a need to overcome or improve upon.

The back-foaming method, however, suffers distinct disadvantages.

Most importantly, the back-foaming or foam injection step requires significantly longer and even a multiple of the time required for carrying out the other product forming steps in the total product forming cycle.

Thus, the foaming step is a production bottleneck.

Furthermore, the foaming equipment and materials require a relatively high capital and material investment.

Also, the finished products comprise a mixture of different synthetic materials firmly bonded together, and thus these products cannot be easily broken down and recycled.

Due to the adhesive layer, it has been found that the cover film and foam layer can slip or shift and thus cause wrinkling or bunching of the cover sheet when the molding lamination is carried out.

Furthermore, the cover film and the foam layer are necessarily pulled and stretched to a greater extent, and thus caused to become thinner, at areas of the pre-formed substrate having sharply curved edges or corners.

As a consequence, the corners, edges and strongly contoured portions of the trim component do not provide an adequate soft-touch characteristic, i.e. these areas feel relatively hard or rigid to the touch.

Disadvantageously in this method, the foam layer and the cover film are heated to a relatively high molding temperature and therefore become soft and deformable during the laminating and molding process.

While an adequate soft-touch effect can be achieved on the flat surface areas, it cannot be achieved at the corners, edges and sharply contoured areas.

A disadvantage of such trim components is that they are hard and do not offer the desired soft-touch characteristic, and furthermore, such trim components can shatter or splinter rather than absorbing energy in impact situations.

Otherwise, the grain previously provided on the film would be crushed.

As a result, the foam and cover film may be pulled or wrinkled in such areas.